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authorRoss Lagerwall <ross.lagerwall@citrix.com>2019-01-17 15:34:38 +0000
committerDavid S. Miller <davem@davemloft.net>2019-01-18 14:05:14 -0800
commit6c57f0458022298e4da1729c67bd33ce41c14e7a (patch)
treec56bc8518423b39cabbda138327a313262ea1e9e
parente40e2a2e78664fa90ea4b9bdf4a84efce2fea9d9 (diff)
net: Fix usage of pskb_trim_rcsum
In certain cases, pskb_trim_rcsum() may change skb pointers. Reinitialize header pointers afterwards to avoid potential use-after-frees. Add a note in the documentation of pskb_trim_rcsum(). Found by KASAN. Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--drivers/net/ppp/pppoe.c1
-rw-r--r--include/linux/skbuff.h1
-rw-r--r--net/bridge/br_netfilter_ipv6.c1
-rw-r--r--net/bridge/netfilter/nft_reject_bridge.c1
-rw-r--r--net/ipv4/ip_input.c1
5 files changed, 5 insertions, 0 deletions
diff --git a/drivers/net/ppp/pppoe.c b/drivers/net/ppp/pppoe.c
index 62dc564b251d..f22639f0116a 100644
--- a/drivers/net/ppp/pppoe.c
+++ b/drivers/net/ppp/pppoe.c
@@ -445,6 +445,7 @@ static int pppoe_rcv(struct sk_buff *skb, struct net_device *dev,
if (pskb_trim_rcsum(skb, len))
goto drop;
+ ph = pppoe_hdr(skb);
pn = pppoe_pernet(dev_net(dev));
/* Note that get_item does a sock_hold(), so sk_pppox(po)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 93f56fddd92a..95d25b010a25 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3218,6 +3218,7 @@ int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len);
*
* This is exactly the same as pskb_trim except that it ensures the
* checksum of received packets are still valid after the operation.
+ * It can change skb pointers.
*/
static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
diff --git a/net/bridge/br_netfilter_ipv6.c b/net/bridge/br_netfilter_ipv6.c
index 94039f588f1d..564710f88f93 100644
--- a/net/bridge/br_netfilter_ipv6.c
+++ b/net/bridge/br_netfilter_ipv6.c
@@ -131,6 +131,7 @@ int br_validate_ipv6(struct net *net, struct sk_buff *skb)
IPSTATS_MIB_INDISCARDS);
goto drop;
}
+ hdr = ipv6_hdr(skb);
}
if (hdr->nexthdr == NEXTHDR_HOP && br_nf_check_hbh_len(skb))
goto drop;
diff --git a/net/bridge/netfilter/nft_reject_bridge.c b/net/bridge/netfilter/nft_reject_bridge.c
index 08cbed7d940e..419e8edf23ba 100644
--- a/net/bridge/netfilter/nft_reject_bridge.c
+++ b/net/bridge/netfilter/nft_reject_bridge.c
@@ -229,6 +229,7 @@ static bool reject6_br_csum_ok(struct sk_buff *skb, int hook)
pskb_trim_rcsum(skb, ntohs(ip6h->payload_len) + sizeof(*ip6h)))
return false;
+ ip6h = ipv6_hdr(skb);
thoff = ipv6_skip_exthdr(skb, ((u8*)(ip6h+1) - skb->data), &proto, &fo);
if (thoff < 0 || thoff >= skb->len || (fo & htons(~0x7)) != 0)
return false;
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 26921f6b3b92..51d8efba6de2 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -488,6 +488,7 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
goto drop;
}
+ iph = ip_hdr(skb);
skb->transport_header = skb->network_header + iph->ihl*4;
/* Remove any debris in the socket control block */